External magnetic fields present in the operating environment of memory devices such as magnetic random access memory (MRAM) devices or in the event of a sabotage or a hacking attempt may cause significant errors in the operation of the MRAM devices. In some cases, the presence of the external magnetic fields may lead to failure of the memory device in performing its intended operation. Therefore, an external magnetic field poses significant risks to the reliability and in some cases to the security of the MRAM devices. Some of the efforts to improve immunity of MRAM devices to external magnetic fields include film stack improvements and packaging shield(s). However, such techniques to improve immunity of MRAM devices to external magnetic fields incur high research and development costs and the achievable immunity would be limited due to the nature of the film characteristics and materials used for the packaging shield.
Accordingly, it is desirable to provide memory devices which are reliable and with enhanced security, particularly for operating in environments susceptible to or with high external magnetic fields.